The present invention relates to a musical tone generator suited for an electronic musical instrument system and, more particularly, to an improvement of a tone generator controller.
As a conventional tone generator having a plurality of musical tone generation channels, a PCM (pulse code modulation) tone generator, an FM (frequency modulation) tone generator, and the like are known. In either type of generator, a same tone color such as a piano is commonly assigned to all of the available channels, e.g., eight channels.
With the prior art technique, even if eight channels are provided for a piano tone color, a performer may use less than 8 channels, e.g., 5 channels, according to his will or a musical piece to be performed, and the remaining channels are left nonused. It is understood that if, e.g., a strings tone color is assigned to the remaining channels, an effective performance is allowed. However, such a tone color assignment cannot be performed in the prior art technique.
In the prior art generator described above, input performance data is indiscriminately received, the presence/absence of an empty channel in a plurality of channels (e.g., 8 channels) is checked, and the input performance data is assigned to the empty channel.
With the prior art technique, the number of musical tones that can be produced at the same time is restricted by the number of channels. For example, when eight channels are arranged, a maximum of eight tones can be simultaneously produced and nine or more tones cannot be simultaneously produced.
Recent electronic musical instruments are often constituted by discrete components. In other words, a keyboard, a sequencer, a music computer, a tone generator unit, and the like are combined to constitute a musical instrument system. In a musical instrument system of this type, a demand often arises for increasing the number of channels according to extension of a keyboard and the like.
In order to satisfy such a demand, a tone generator unit or units may be extended. However, if they are simply extended, the number of musical tones that can be produced at the same time cannot be increased. More specifically, if a plurality of tone generator units each having a plurality of channels are arranged, and given performance data is input thereto, each tone generator unit indiscriminately receives the performance data to execute musical tone generation processing. Therefore, a plurality of tones having pitches corresponding to the performance data can be parallel-generated from the plurality of tone generator units. These tones essentially correspond to one tone since they have the same pitch. For example, even if two tone generator units each having eight channels are arranged, a maximum of only eight tones can be simultaneously produced.
In such a case, in order to increase the number of musical tones that can be simultaneously produced, the arrangement and processing mode of the tone generator unit or units can be updated to correspond to an increased number (e.g., 16) channels. However, it is very inconvenient to perform such updating every time a tone generator unit or units are extended.